Organic carbonates such as the dialiphatic carbonates, aliphatic aromatic carbonates, and diaromatic carbonates are generally conventionally prepared by the reaction of phenols or alcohols with phosgene in the presence of acid binding agents such as the organic bases or inorganic bases. However, due to the toxicity of phosgene it is sometimes desirable to avoid the use of phosgene in the preparation of these organic carbonates.
Since the dialiphatic carbonates, such as the dialkyl carbonates, may be prepared from alcohols by routes other than those utilizing phosgene, i.e., catalytically from carbon monoxide and oxygen, it is possible to prepare the aliphatic aromatic carbonates and the diaromatic carbonates from these dialiphatic carbonates and phenols without using phosgene. Such phosgene free processes are disclosed in U.S. Pat. Nos. 4,045,464 and 4,182,726. These patents disclose the preparation of alkyl aryl carbonates and diaryl carbonates by the reaction of phenols with dialkyl carbonates or alkyl aryl carbonates in the presence of a Lewis acid catalyst. The Lewis acid catalysts disclosed in these patents are compounds having the formulae AlX.sub.3, TiX.sub.3, UX.sub.4, TiX.sub.4, VOX.sub.3, VX.sub.5, ZnX.sub.2, FeX.sub.3, and SnX.sub.4, wherein X is halogen, acetoxy, alkoxy, or aryloxy.
It would, however, be advantageous if a transesterification process could be provided which is more efficient, from the standpoint of providing higher conversion rates of the dialkyl carbonates to the alkyl aryl carbonates and the diaryl carbonates, particularly to the diaryl carbonates, than the presently available processes. It is, therefore, an object of the instant invention to provide such a process.